A Modified Double-Integral-Sliding-Mode-Controller for a Microgrid System With Uncertainty

Abstract

Recently infiltration of large scale of microgrid systems into the power grid isrecorded. Among these systems, photovoltaic (PV) based microgrid systemsare more in demand due to its renewable, pollution free properties andabundantly available fuel. Grid integration of this microgrid system againenhanced its energy efficiency. But, dynamics of this PV based microgridsystem is highly nonlinear and uncertain in nature. It suffers from para-metric uncertainties. This kind of system can’t be controlled properly byconventional linear controllers. Sliding mode controller (SMC) is capableof controlling this kind of system with ease. However, SMC suffers from itsinherent chattering introduction in the system output waveform. To reduce thechattering from the output waveform, there is requirement of some modifica-tion in the existing SMC structure dynamics. This paper presents an extendedstate observer based double integral sliding mode controller (DISMC) for thisstudied system. By using DISMC, the chattering magnitude is diminishedgreatly. Parameter uncertainties of the system lead to some unknown controlstates. These unknown states are identified by the state observer. Therefore,the proposed controller is more efficient in reference tracking, disturbance rejection and robust stability. To test the efficacies of the proposed controller,results of the studied system with this controller are compared with that ofH∞ controller.